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First hamon attempt, please advise


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This is my first try at a hamon and I’m also pretty new to bladesmithing so I wasn’t expecting great success but I certainly was not expecting what I got either. 
 

First off, the steel is 1075 from NJSB. The Mn content in this batch is 0.434 which I’ve read is a little on the high side for hamon but thought I’d give it a go anyway. 
 

I forged the blade by hand then normalized and annealed in vermiculite. 

 

After refining the profile and roughing in the bevels on the grinder I hand sanded to 120 grit. 


I’ll include a picture below of the blade with the clay applied. Using hamon 1800 clay I did my best to keep the thickness consistent along the length of the blade. It wound up being between 1/16 and 3/32 I think. 

 

After allowing the clay to dry thoroughly I austenitized at 1475-1480 (according to the thermocouple in my forge) and soaked for about 5 min before quenching in parks50 heated to around 70 degrees. 

 

The blade did not warp and the clay mostly stayed on. In fact it was quite difficult to remove. 

 

Tempered one hour at 350 and then 2 hours at 375-400 (according to the oven thermometer in my toaster oven). 

 

I ground and sanded and polished all the way to 2000 grit then etched with lemon juice twice and vinegar once removing the oxides in between. 

 

Long story short, I followed all the advice I could find on the internet haha. As you can see I definitely produced a hamon but it is not pretty. Also I am confused as to why it widens and fades to nothing as it nears the tip. Was my clay too thin? Too thick? Temperature too high? I have already guessed that the pattern in which I applied the clay was not helping me. 


Please chime in with any advice! I’m already addicted to this hamon stuff and I want to do it better next time!

 

Thanks in advance

-David

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Nice forging! I'm not an expert in this, but I do a lot of traditional Japanese polishing, so I'll go from that perspective. You can see some faint traces like a wavy hamon on the tip, and it looks like there are two lines at the base, the line at the bottom of the edge, and a second line which is sort of wavy below that. I would say at least at the base, you probably have a straight or suguha hamon there, the waves being a secondary sort of pattern of softer steel (this happens with a wavy clay pattern, as you used). The hamon dissappears as you approach the tip, so I'd say more polishing there is necessary to see what you've really got. Using really light pressure with sandpaper helps bring out the hamon better, as does longer time with the etch. 

 

Again, not an expert, but I think the blade got too hot before the quench. It's a delicate balance, you have to get it through decalescence/recalescence, but you don't want to leave it heating up too long either, or the heat will migrate into the clay. I'll let the real experts comment a bit more though!

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Also not an expert, but the soak is what did it.  Do not soak 1075, it's good to go when it hits 1425 F.  Also don't bother with the vermiculite, just normalize.  You'll get better grain structure.  

 

The clay thickness is fine.  It can be a little thicker towards the spine, but it doesn't have to be.

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Thank you for the replies!

 

Carlos, I did two more applications of lemon juice last night with a gentle polish after each to try to bring out more detail but I did not see any change in the pattern. Maybe I’m still being too aggressive with the polishing. 
 

Alan, I did the soak according to heat treatment recommendations in the Knife Engineering book by Dr Larrin Thomas. But I didn’t think about how that would translate to the creation of a hamon. I am going to normalize the blade again and start over with the clay. This time I’ll get it up to temp and go straight to the quench. 
 

Thanks again for the input!

 

-David

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When you polish with sandpaper, even a rough grit very softly, with enough polishing the soft steel gets a sort of light grey colour/satin texture, whereas the hardened steel is always smoother and brighter. The interface between these two is your true "hamon line." It's not that easy to get it though, so if you're not sure, then I think normalizing and trying again is the way to go. Once you burnish though, as you have a bit, you need to go back to coarse grits again to open up the grain pattern.

Edited by Carlos Lara
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That is a nice looking blade. I agree with Alan , no need to soak. Remember,the edge is what you need to harden not a 1 inch block. Stainless is different. But for simple tool steel , get it to temp and quench. That hamon looks lovley. Cheers

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It looks like you have both an auto hamon and one caused by the clay. This can be caused by various factors such as an uneven temperature between surface and depth (colder core, usually at spine where it's thickest), overall geometry of the cross section, use of a slow quenchant, too much clay, or both.

 

Edit: and if you mean by "soak" that you put the blade in there and waited 5 minutes, it may be the issue here. Thicker cross sections may require more than that to get up to temp. 

Edited by Joël Mercier
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Thanks all. Next steps will be sand back to 120 grit, normalize, clay, austenitize (with no soak this time), quench in parks 50, temper at 350 and polish meticulously. Hopefully I will get a different result even if it’s still not great. Progress is progress, right? haha. 
 

Note: Joël, I started the soak after the entire blade, including the clay, was the same color as my thermocouple that was reading 1470. Thanks for asking though. It’s good for me to go back and mentally check my methods. 

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